Selecting a safer vehicle is a lot easier than it used to be.

Most new cars, minivans, pickups and SUVs earn good ratings in most crash tests conducted by the Insurance Institute for Highway Safety (IIHS) and the National Highway Traffic Safety Administration (NHTSA). Some models still need improvement when it comes to protecting people in rollovers, rear crashes and certain types of front crashes. So how is a safety-conscious buyer to choose? The information here, along with our vehicle ratings, can help you identify the best picks.

Whether you are in the market for a new or used vehicle, here are some things to consider:

Vehicle size and weight matter. Smaller, lighter vehicles generally offer less protection than larger, heavier ones. There is less structure to absorb crash energy, so deaths and injuries are more likely. People in lighter vehicles also experience higher crash forces when struck by heavier vehicles. If safety is a major consideration, pass up very small, light vehicles.

A crashworthy design reduces death and injury risk. Structure and restraints help determine crashworthiness. Good structure means a strong occupant compartment, crumple zones to absorb the force of a serious crash, side structure to manage the force of a striking vehicle or struck object and a strong roof that won't collapse in a rollover. Safety belts keep people in their seats and spread crash forces across the upper body's stronger bony parts. Airbags protect people from hitting things inside the vehicle or objects outside it.

Vehicle ratings and crash tests

A good place to start your research is in our vehicle ratings section. Each year, IIHS rates new models based on how well they protect people in front, side, rollover and rear crashes. IIHS also rates the performance of front crash prevention systems, including forward collision warning and automatic braking. Models with the highest ratings qualify for an IIHS safety accolade.

To earn a Top Safety Pick+ award, models must achieve good ratings in the moderate overlap front, side, roof strength and head restraint tests; a good or acceptable rating in the small overlap front test; and an advanced or superior rating for front crash prevention.

Models that meet the crash test ratings criteria but have a basic-rated front crash prevention system or no system at all qualify for Top Safety Pick.

NHTSA also identifies models with advanced features such as lane departure warning, forward collision warning and rearview cameras.

Front crash prevention | adaptive headlights

Crash avoidance technologies

Protecting people in crashes is vital. Avoiding them altogether is ideal. Crash avoidance systems can help. Many automakers offer them on 2015 models. So far two features — front crash prevention and adaptive headlights — are reducing crashes, based on analysis of insurance losses by the Highway Loss Data Institute (HLDI), an affiliate of IIHS.

Front crash prevention systems fall into two categories: forward collision warning and autobrake. Warning systems alert you if you get too close to a car in front. Autobrake systems can brake if you don't respond in time. Others brake without warning you first.

Adaptive headlights shift direction as you steer to help you see better on curves in the dark. Lane departure warning and blind spot detection are two other technologies intended to help drivers avoid crashes. So far, IIHS and HLDI haven't been able to quantify their benefits.

Buying a used vehicle

IIHS has been awarding Top Safety Pick since 2006 and Top Safety Pick+ since 2012. Here are some things to help assess the crashworthiness of older models:

Frontal crashworthiness — Look for good ratings in frontal tests. Most newer models earn top marks for frontal crashworthiness in NHTSA' 35 mph test head-on into a rigid barrier and the IIHS 40 mph moderate overlap test into a deformable barrier. Drivers of vehicles rated good in the IIHS test are about 46 percent less likely to die in a serious frontal crash than drivers in poor-rated vehicles.

Side crashworthiness — Choose a vehicle with good side ratings plus side airbags that protect your head. IIHS and NHTSA rate models based on tests that simulate front-into-side crashes. The tests represent different side impact dangers. Shoppers wanting the best protection should look for vehicles with the highest ratings in all conditions. Drivers of vehicles with good ratings in the IIHS side barrier test are 70 percent less likely to die in a driver-side crash compared with drivers in vehicles rated poor. Likewise, studies of real-world crashes indicate that side airbags substantially reduce fatality risk. Some side airbags also are designed to protect you in a rollover. The majority of 2008 and later models have side airbags as standard equipment.

Roof strength — Look for a strong roof. IIHS rates roof strength to help consumers pick vehicles with roofs that will hold up in a rollover crash. Stronger roofs crush less. Ratings began with 2008-09 models.

Head restraints — Pick a model with a good seat/head restraint rating to reduce whiplash injuries in a rear-end collision. Vehicles with seat/head restraint combinations rated good by IIHS have 15 percent fewer insurance claims for neck injuries than vehicles with poor ratings. You can help increase protection by remembering to adjust the head restraint to correctly fit behind your head.

Electronic stability control — Buy a vehicle with ESC. It's standard on 2012 and later models and available on many earlier ones. An extension of antilock brake technology, ESC engages automatically to help drivers maintain control on curves and slippery roads. ESC lowers the risk of a fatal single-vehicle crash by about half and the risk of a fatal rollover by as much as 80 percent.